This 1998 relic asks a question modern anime won't touch: what if Earth was already dead, and these kids are humanity's last argument with extinction? The world-building is patient, deliberate, sometimes glacially slow, but it trusts you to sit with the strangeness of a polluted Earth, child labor systems, and a substance called DT that rewrites what it means to be human. Animation budget this thin would sink anything else, but the concept is strange enough to carry you through 26 episodes of asking what Zero actually wants and whether Shu can survive knowing the truth.

Shu lives in Datania, a closed-off city where children are put to work and people feel nothing. When Shu begins to develop feelings, he and his friends try to escape, and along the way they meet the Returners, rebels who oppose Datania. Beyond the city lies a world in ruins, home to survivors badly burned by ultraviolet rays. Shu joins the Returners in their fight against Zero, Nines and their men, who are after DT, a special substance found inside humans. Throughout his journey, a mysterious robot called Eightron comes to his aid whenever things turn critical.